Xamarin android save text file

问题

I am using Xamarin.Android and I want to save a .txt file to the SD card. Here is the code that I am using:

  private void SavetoSd()
  {
       var sdCardPath = Android.OS.Environment.ExternalStorageDirectory.Path;
       var filePath = System.IO.Path.Combine(sdCardPath, "iootext.txt");
       if (!System.IO.File.Exists(filePath))
       {
           using(System.IO.StreamWriter write = new System.IO.StreamWriter(filePath,true))
           {
               write.Write(etSipServer.ToString());
           }
       }    
  }

However, I receive the following error:

System.UnauthorizedAccessException: Access to the path "/mnt/sdcard/iootext.txt" is denied.

I have added the following to the manifest:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

How can I fix the error?

回答1:

If you're on Android 6.0+ you will need to perform a runtime check for permissions. This can be done like so:

if ((CheckSelfPermission(Permission.ReadExternalStorage) == (int)Permission.Granted) && 
    (CheckSelfPermission(Permission.WriteExternalStorage) == (int)Permission.Granted))

More information on this can be found in the android documentation here.

回答2:

If file does not exist first create, than get the absolute path and write your data into it.

     Java.IO.File sdCard = Android.OS.Environment.ExternalStorageDirectory;
     Java.IO.File dir = new Java.IO.File (sdCard.AbsolutePath + "/MyFolder");
     dir.Mkdirs ();
     Java.IO.File file = new Java.IO.File (dir,"iootext.txt");
        if (!file.Exists ()) {
            file.CreateNewFile ();
            file.Mkdir ();
            FileWriter writer = new FileWriter (file);
            // Writes the content to the file
            writer.Write (jsonData);
            writer.Flush ();
            writer.Close ();
        }

回答3:

I was having same problem and after spending couple of hours, I found that if you are running on sdk higher than 23, android version higher than 6, you should implement access request to user. please find more information here on this link

来源：https://stackoverflow.com/questions/36545008/xamarin-android-save-text-file

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android

Xamarin

xamarin.android